Liver and spleen as venous reservoirs

Abstract

The diameter of the liver and spleen was measured in 37 intact unanesthetized dogs. Fright always produced vigorous contraction of the spleen but no appreciable change in the liver. Running on a treadmill caused splenic contraction in only one-half the instances. The liver usually got larger or did not change with exercise. Epinephrine caused prompt contraction of the spleen and a variable response of the liver with no change in over one-half the trials. Several other drugs produced splenic contraction, apparently through reduction of blood pressure. Hemorrhage invariably produced splenic contraction, with average volume changes of 8% of the total blood volume. Hemorrhage caused a gradual decrease in liver size in only one-half the animals. Hypoxia caused extremely vigorous contractions of the spleen, usually accompanied by an increase in liver size. In short, in the dog the spleen is a precisely regulated reservoir, but the liver is not. However, vigorous exercise may be initiated and maintained without contributions from either organ.